1. Field of the Invention
The present invention relates to a support structure for a viewfinder mirror movably mounted in a single lens reflex camera. More particularly, the present invention relates to a buffer for such a mirror.
2. Description of the Prior Art
Conventionally, the viewfinder mirror in a single lens reflex camera is rotatably mounted so that it can move between two positions i.e. working position and retracted position. When the operator is viewing the object through a finder eyepiece, the viewfinder mirror is held in the optical path of the object light from a photographing lens to reflect the object light beam toward the finder optical system. This position is the working position of the viewfinder mirror. Immediately before the start of exposure on the film, the mirror is brought to a position out of the optical path of the object light. This position is the retracted position.
The shift of the mirror from the working position to the retracted position is generally achieved by rotating the mirror about a rotation axis along one edge of the mirror by about 45 degrees. When the mirror reaches the position in which the mirror surface is substantially parallel to the optical axis of the photographing lens, the rotation of the mirror is stopped. At the stop, the mirror is apt to rebound due to shock. If a portion of the rebounding mirror enters the optical path of the object light, the object image on the film may be impaired.
After the completion of film exposure, the mirror is again turned down to the working position in the optical path of the object light. When stopped at the working position, the mirror is again subjected to shock which may cause the stopped mirror to unbound in an oscillatory manner. Such rebounding of the mirror at the stop in the working position may hinder the operator from viewing the object through the viewfinder because the object image formed on the finder screen oscillates at that time. The problem is exacerlated in particular when a continuous shooting is performed using a motor drive unit. In this picture-taking mode, the mirror-up and mirror-down movements are repeated many times at very short intervals and, therefore, the time during which the object image is stable is very short. Because of this, the viewing of the object image as well as focusing are rendered very difficult.
In order to solve the problem, there have been proposed many buffers for the rotatable viewfinder mirror of the type mentioned above. However, almost all of the prior buffers for viewfinder mirrors are not satisfactory. Some of them need a complicated additional mechanism and some of them cannot produce an adequate effect to damp mirror shock.